Al Gore says global warming is a planetary emergency. It is difficult to see how this can be so when record low temperatures are being set all over the world. In 2007, hundreds of people died, not from global warming, but from cold weather hazards.

Since the mid-19th century, the mean global temperature has increased by 0.7 degrees Celsius. This slight warming is not unusual, and lies well within the range of natural variation. Carbon dioxide continues to build in the atmosphere, but the mean planetary temperature hasn’t increased significantly for nearly nine years. Antarctica is getting colder. Neither the intensity nor the frequency of hurricanes has increased. The 2007 season was the third-quietest since 1966. In 2006 not a single hurricane made landfall in the U.S.

South America this year experienced one of its coldest winters in decades. In Buenos Aires, snow fell for the first time since the year 1918. Dozens of homeless people died from exposure. In Peru, 200 people died from the cold and thousands more became infected with respiratory diseases. Crops failed, livestock perished, and the Peruvian government declared a state of emergency.

Unexpected bitter cold swept the entire Southern Hemisphere in 2007. Johannesburg, South Africa, had the first significant snowfall in 26 years. Australia experienced the coldest June ever. In northeastern Australia, the city of Townsville underwent the longest period of continuously cold weather since 1941. In New Zealand, the weather turned so cold that vineyards were endangered.

Last January, $1.42 billion worth of California produce was lost to a devastating five-day freeze. Thousands of agricultural employees were thrown out of work. At the supermarket, citrus prices soared. In the wake of the freeze, California Gov. Arnold Schwarzenegger asked President Bush to issue a disaster declaration for affected counties. A few months earlier, Mr. Schwarzenegger had enthusiastically signed the California Global Warming Solutions Act of 2006, a law designed to cool the climate. California Sen. Barbara Boxer continues to push for similar legislation in the U.S. Senate.

In April, a killing freeze destroyed 95 percent of South Carolina’s peach crop, and 90 percent of North Carolina’s apple harvest. At Charlotte, N.C., a record low temperature of 21 degrees Fahrenheit on April 8 was the coldest ever recorded for April, breaking a record set in 1923. On June 8, Denver recorded a new low of 31 degrees Fahrenheit. Denver’s temperature records extend back to 1872.

Recent weeks have seen the return of unusually cold conditions to the Northern Hemisphere. On Dec. 7, St. Cloud, Minn., set a new record low of minus 15 degrees Fahrenheit. On the same date, record low temperatures were also recorded in Pennsylvania and Ohio.

Extreme cold weather is occurring worldwide. On Dec. 4, in Seoul, Korea, the temperature was a record minus 5 degrees Celsius. Nov. 24, in Meacham, Ore., the minimum temperature was 12 degrees Fahrenheit colder than the previous record low set in 1952. The Canadian government warns that this winter is likely to be the coldest in 15 years.

Oklahoma, Kansas and Missouri are just emerging from a destructive ice storm that left at least 36 people dead and a million without electric power. People worldwide are being reminded of what used to be common sense: Cold temperatures are inimical to human welfare and warm weather is beneficial. Left in the dark and cold, Oklahomans rushed out to buy electric generators powered by gasoline, not solar cells. No one seemed particularly concerned about the welfare of polar bears, penguins or walruses. Fossil fuels don’t seem so awful when you’re in the cold and dark.

If you think any of the preceding facts can falsify global warming, you’re hopelessly naive. Nothing creates cognitive dissonance in the mind of a true believer. In 2005, a Canadian Greenpeace representative explained global warming can mean colder, it can mean drier, it can mean wetter. In other words, all weather variations are evidence for global warming. I can’t make this stuff up.

Global warming has long since passed from scientific hypothesis to the realm of pseudo-scientific mumbo-jumbo.

David Deming is a geophysicist, an adjunct scholar with the National Center for Policy Analysis, and associate professor of Arts and Sciences at the University of Oklahoma.